Bottom Line:
In each tested S. mutans strain, biomass was significantly decreased (SNK test, p < 0.05) in the P85F and F biofilms relative to untreated biofilms.Parallel CFU/ml determinations revealed that biofilm growth in the presence of P85F resulted in a 3-log reduction in viability, whereas F decreased viability by less than 1-log.Collectively, these results suggest that Pluronics-formulated farnesol induces alterations in biofilm architecture, presumably via interaction with the sucrose-dependent biofilm matrix, and may be a viable treatment option in the prevention and treatment of pathogenic plaque biofilms.

Affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, 32611, United States of America.

ABSTRACTStreptococcus mutans is the primary causative agent of dental caries, one of the most prevalent diseases in the United States. Previously published studies have shown that Pluronic-based tooth-binding micelles carrying hydrophobic antimicrobials are extremely effective at inhibiting S. mutans biofilm growth on hydroxyapatite (HA). Interestingly, these studies also demonstrated that non-binding micelles (NBM) carrying antimicrobial also had an inhibitory effect, leading to the hypothesis that the Pluronic micelles themselves may interact with the biofilm. To explore this potential interaction, three different S. mutans strains were each grown as biofilm in tissue culture plates, either untreated or supplemented with NBM alone (P85), NBM containing farnesol (P85F), or farnesol alone (F). In each tested S. mutans strain, biomass was significantly decreased (SNK test, p < 0.05) in the P85F and F biofilms relative to untreated biofilms. Furthermore, the P85F biofilms formed large towers containing dead cells that were not observed in the other treatment conditions. Tower formation appeared to be specific to formulated farnesol, as this phenomenon was not observed in S. mutans biofilms grown with NBM containing triclosan. Parallel CFU/ml determinations revealed that biofilm growth in the presence of P85F resulted in a 3-log reduction in viability, whereas F decreased viability by less than 1-log. Wild-type biofilms grown in the absence of sucrose or gtfBC mutant biofilms grown in the presence of sucrose did not form towers. However, increased cell killing with P85F was still observed, suggesting that cell killing is independent of tower formation. Finally, repeated treatment of pre-formed biofilms with P85F was able to elicit a 2-log reduction in viability, whereas parallel treatment with F alone only reduced viability by 0.5-log. Collectively, these results suggest that Pluronics-formulated farnesol induces alterations in biofilm architecture, presumably via interaction with the sucrose-dependent biofilm matrix, and may be a viable treatment option in the prevention and treatment of pathogenic plaque biofilms.

Mentions:
In addition to inhibition of biofilm formation, farnesol-formulated Pluronic micelles were tested for their effect on viability and architecture of pre-formed biofilms (Figs 4 and 5). Repeated treatment of pre-formed UA159 biofilms with either P85F or F alone (Fig 4B and 4C) over a three day period resulted in biofilms with decreased biomass (Fig 5A) and increased roughness (Fig 5B) relative to biofilms treated with P85 alone or untreated biofilms (Fig 4A and 4D). Furthermore, formation of cell death towers was also sporadically observed in pre-formed biofilms treated with P85F (Fig 4B), whereas pre-formed biofilms treated with F alone contained an evenly-distributed mixture of live and dead cells throughout the biofilm (Fig 4C). In parallel experiments, pre-formed biofilms treated with P85F experienced a 2-log decrease in cell viability relative to untreated biofilms, and treatment with F alone only reduced biofilm viability by 0.5-log (Fig 5C). These results demonstrate that tower formation and significant cell death are features common to S. mutans biofilms treated with P85F.

Mentions:
In addition to inhibition of biofilm formation, farnesol-formulated Pluronic micelles were tested for their effect on viability and architecture of pre-formed biofilms (Figs 4 and 5). Repeated treatment of pre-formed UA159 biofilms with either P85F or F alone (Fig 4B and 4C) over a three day period resulted in biofilms with decreased biomass (Fig 5A) and increased roughness (Fig 5B) relative to biofilms treated with P85 alone or untreated biofilms (Fig 4A and 4D). Furthermore, formation of cell death towers was also sporadically observed in pre-formed biofilms treated with P85F (Fig 4B), whereas pre-formed biofilms treated with F alone contained an evenly-distributed mixture of live and dead cells throughout the biofilm (Fig 4C). In parallel experiments, pre-formed biofilms treated with P85F experienced a 2-log decrease in cell viability relative to untreated biofilms, and treatment with F alone only reduced biofilm viability by 0.5-log (Fig 5C). These results demonstrate that tower formation and significant cell death are features common to S. mutans biofilms treated with P85F.

Bottom Line:
In each tested S. mutans strain, biomass was significantly decreased (SNK test, p < 0.05) in the P85F and F biofilms relative to untreated biofilms.Parallel CFU/ml determinations revealed that biofilm growth in the presence of P85F resulted in a 3-log reduction in viability, whereas F decreased viability by less than 1-log.Collectively, these results suggest that Pluronics-formulated farnesol induces alterations in biofilm architecture, presumably via interaction with the sucrose-dependent biofilm matrix, and may be a viable treatment option in the prevention and treatment of pathogenic plaque biofilms.

Affiliation:
Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, 32611, United States of America.

ABSTRACTStreptococcus mutans is the primary causative agent of dental caries, one of the most prevalent diseases in the United States. Previously published studies have shown that Pluronic-based tooth-binding micelles carrying hydrophobic antimicrobials are extremely effective at inhibiting S. mutans biofilm growth on hydroxyapatite (HA). Interestingly, these studies also demonstrated that non-binding micelles (NBM) carrying antimicrobial also had an inhibitory effect, leading to the hypothesis that the Pluronic micelles themselves may interact with the biofilm. To explore this potential interaction, three different S. mutans strains were each grown as biofilm in tissue culture plates, either untreated or supplemented with NBM alone (P85), NBM containing farnesol (P85F), or farnesol alone (F). In each tested S. mutans strain, biomass was significantly decreased (SNK test, p < 0.05) in the P85F and F biofilms relative to untreated biofilms. Furthermore, the P85F biofilms formed large towers containing dead cells that were not observed in the other treatment conditions. Tower formation appeared to be specific to formulated farnesol, as this phenomenon was not observed in S. mutans biofilms grown with NBM containing triclosan. Parallel CFU/ml determinations revealed that biofilm growth in the presence of P85F resulted in a 3-log reduction in viability, whereas F decreased viability by less than 1-log. Wild-type biofilms grown in the absence of sucrose or gtfBC mutant biofilms grown in the presence of sucrose did not form towers. However, increased cell killing with P85F was still observed, suggesting that cell killing is independent of tower formation. Finally, repeated treatment of pre-formed biofilms with P85F was able to elicit a 2-log reduction in viability, whereas parallel treatment with F alone only reduced viability by 0.5-log. Collectively, these results suggest that Pluronics-formulated farnesol induces alterations in biofilm architecture, presumably via interaction with the sucrose-dependent biofilm matrix, and may be a viable treatment option in the prevention and treatment of pathogenic plaque biofilms.